const imgEl = document.querySelector("img")
// imgEl1: HTMLImageElement | null

const imgEl1 = document.querySelector(".img")
// imgEl: Element | null

const imgEl2 = document.querySelector(".img") as HTMLImageElement
// imgEl2: HTMLImageElement


const age: number = 18
const age2 = age as string // 报错
const age3 = age as any // 不报错


export {}